Liquid fuel supply device



May 15, 1951 R. w. JOHNSON 2,552,633

LIQUID FUEL SUPPLY DEVICE Filed Deo. 26, 1947 H lll INVENTOR. E05/ PV.JOH/VSN WMWJM iiatenfed May 15, i951 UNITED STATES PATENT OFFIC2,552,633 LIQUID FUEL sUPrLY DEVICE Roy W. Johnson, Milwaukee, Wis.

Application December 26, 1947, Serial No. 793,975

Claims. (Cl. 10S-25) This invention relates to improvements in def vicesforsupplyinng liquid fuel to burners from a source of supply remote fromsuch burner.

I n my Patent No. 2,445,069 I have shown a pumping mechanism which isadapted to deliver liquid fuel to a control device under a substantiallyconstant hydrostatic head. The pumping mechanism utilizes a bypassassociated with the pump and separate means to disconnect the pump motorif the liquid level increases over a predetermined maximum. The presenceof the by-pass brings in leakage problems and increases the chances ofclogging, while the extra control means complicates the device.

It is one object of the `present invention to provide a device forsupplying liquid fuel to a burner which does not require theincorporation of lay-passes and separate cutoff devices for the pumpm-otor.

Another object of the invention is to provide a `device of this typewhich is of simple construction, less liable to clog in operation, andwhich .is relatively inexpensive to manufacture.

These objects are obtained by providing a oo ntinuously energized motorfor operating -a pump to maintain a given minimum pressure on the'val-ve which regulates the admission of liquid to the control chamber;the operation of the .motor driven pump and its delivery of liquidVbeing controlled by an increase in the discharge pressure above a givenvalue. Thus the delivery -of liquid fuel -is accomplished without resortto by-passes or separate means for disconnecting the motor from itssource of power. This device can Abe manufactured, therefore, at a lowercost than the mechanism shown in my prior Patent No. 2,445,069.

Objects and advantages other than those above :set forth will heapparent from the following description when read in connection with theaccompanying drawing in which:

Fig. 1 `is a view partially in section and partially in elevation of oneembodiment of .the present invention.

Fig. 2 is a view partially in section and partially in elevation of asecond embodiment of the present invention; and

Fig. 3 is a top plan View of one element of the structure shown in Fig.2.

The present combina-tion generally includes a continuously `energized.electric motor driving a pump of the positive displacement type,drawing a liquid fuel from a tank or source. The pump discharges into aconduit leading toa .casing into which `liquid ilow is controlled by avalve lbiased to its open position and urged to its seated position :bya float shifting as ythe liquid level within the casing varies. Ametering valve associated with the casing, controls ow'of fuel to aspace heater and is adjustable to different positions as the rate ofcombustion of the burner is to be changed. Adjustment of the meteringvalve may be manual or may be by automatic means thermostaticallycontrolled from a location remote from the burner.

Referring particularly to the drawings, numeral 5 designates a conduitfrom a liquid fuel source or tank (not shown) at a location below andremote from the space to be heated, Such conduit is connected with acasing 6 forming a portion of a positive displacement or constant volumepump, the impeller l of such pump being indicated as of the sliding vanetype although it will be understood that other types of .positivedisplacement rotary impellers may be used such as shiftable vanes. Ashaft 9 extends from the pump impeller 1 through a suitable packing'A i0in the pump casing.

The pump c asing 6 has mounted thereon 4a housing I3 for enclosing powermeans driving the pump, which means are herein shown as an electricmotor I4 of the shaded pole induction type. The shaft I5 of the motor,is connected directly with the .pump shaft 9 through a flexible coupling,I6 herein shown as a helical spring which permits relative movementbetween th'e pumpV rotor and the motor rotor.

A discharge passage 20 in the pump casing 6 is connected with the inletend of a passage 2 yI'ofa well know-n type of liquid level controldevice. Itis ythe function of such device to `supply liquid fuel to theburner at 'a substantially `constant hydraulic head regardless of thepressure inthe passages 20 and 2l. The liquid `leveldevice or owcontr-ol means includes a casing 24 in which is mounted an inlet valveindicated at 25 resiliently urged in the opening direction iby a spring26. A float 21 is pivotally mounted on a bracket 28 in casing 2li and`acts on the inlet valve 2-5 .to -urge such valve in closing directionas the liquid fuel within the casing rises -tothe desired levelindicated uin the drawing.

Fuel is allowed to flow by gravity from the control device to a burner(not shown) under -t'he control of an adjustable outlet valve 33connected with a .conduit 34. The outlet valve 33 is urged in .theopening direction by a spring 3E and the degree 'of opening of .theval-ve is controlled `by a l ably mounted in the top 4l of the casing 24and has an -adjustable cam member 42 mounted on the end thereof withinthe casing. The cam is engageable with an ear 46 extending from a lever4l pivoted in the casing and bearing a leaf spring 48 extending over theoutlet valve for movement into and out of contact with the end of thevalve upon adjustment of such valve to Various positions as the knob isrotated to vary the portion of the cam in contact with the lever ear 46.

The electric motor I4 isV continuously connected to the source ofelectric power 18 and causes the pump to supply fuel under pressure tothe inlet passage 2U. However, if the liquid level device is satisfied,the inlet valve 25 is closed. This causes the pressure at the deliveryside of the pump to increase. At a predetermined in crease the motor I4will stall. However, the shaded pole induction motor, when stalled,draws only a little more current than when running and hence will notoverheat. The motor and pump remain stalled until the liquid leveldevice` calls for more liquid. Y

vThe modication of the present invention,

shown in Figs. 2 and 3, differs from the structure above described byhaving the pump casing 5 provided with a wall 55 which, together with aWall 56 mounted on such casing, encloses a space divided into twochambers 5l and 58 by a resilient 'diaphragm 59. The pump dischargepassage 2B is now connected by a conduit 5d with chamber 5l and suchchamber is connected with the inlet passage 2l of the valved controlmeans. The wall 55 has mounted therein a guide 65 for push rod 66 whichextends from the chamber into the space enclosed by the motor housingI3. A plate 6l, engageable with one end of the guide, forms one bearingsurface for a helical spring 68 bearing at its other end on a plate 69fixed on the diaphragm 59, the plate 69 providing a surface on which oneend of the rod E6 may also bear. It is possible to adjust the spring 68by screwing. the guide 65 inwardly to move the plate 6l ,and compressthe spring. The other end of the rod 66 is formed to provide a universaljoint i3 supporting brake shoe lll with brake lining i5 to bear againstthe edge of a disk i6 fixed onmotor shaft I6.

' As previously explained, the motor i4 is con-'- tinuously energizedand the pump 5, 1, being of the positive displacement type, dischargesfuel under pressure whenever the shaft I5 rotates. So long as the flowcontrol means requires liquid fuel for the burner, substantially all theoutput of the pump will be required and the pressure in the conduit 20and inlet passage 2l remains substantially constant. However, if lessfuel is required by the burner, the level of fuel in the control casing24 rises and float 21 closes the inlet valve 25. Continued operation ofthe motor l5 and pump 6, 'l then builds up pressure in the pumpdischarge passage 20.

This pressure builds up on diaphragm 59 and compresses spring 68 untilpressure plate 69 presses on the end of rod 66. Brake shoe 'I4-i5 isthen pressed against the edge of disk -l slowing down the motor and thepump, until the required amount of fuel is delivered or until the motori4 stalls. l

It will be seen that the present device .provides a power-driven pumpcontinuously maintaining a predetermined minimum pressure on the inlet'valve of flow control means which in turn maintains a given hydraulichead on the llow control means outlet valve, except for small andrelative infrequent variations in head as the quantity of fuel iowing tothe burner is varied. Power is continuously applied to the pump so thatthe pump is ready for operation at all times and the pump-motor merelystalls when the pump discharge pressure exceeds a predetermined value.When the motor has stalled, continued energization of the motor holdsthe pump in substantially a given position and causes the pump to act asa check or non-return valve. The flexible coupling between the motor andpump shafts reduces the effect of stalling on the motor and may act assource of power to keeprpressure on the fuel until a minimum value isagain .-.reached whereupon the pump restarts. This simple constructioneliminates by-passes subject to clogging and additional power cut-ofimeans, thus' making the unit more effective and practical and lesseningits cost of manufacture.

Although but two embodiments of the present invention have beenillustrated and described, it will be apparent to those skilled in theart that various changes and modifications may be made therein withoutdeparting from the spirit of the invention or from the scope of theappended claims.

v I claim: ,Y l. in a device for supplying liquid fuel to a burner, achamber, a valve controlling flow Vof fuel into'the chamber undercontrol of change of liquid level therein, a continuously energizedvshaded pole induction type electric motor, a constant volume pump drivenby said motor for maintaining a supply of fuel to said valve, a brakefor retarding the operation of said pump, and means responsive to pumpdischarge pressure above a given value for actuating the brake.

2. A device for supplying liquid fuel to a burner as claimed in claimV1, in which said means consist of a diaphragm one side of which isconnected to the discharge side of said pump and the movable portion ofWhich' is connected to said brake. l

3. In a device for supplying liquid fuel to a burner, a chamber, a valvecontrollingflow'of fuel into the chamber under control of change ofliquid level therein, a continuously energized motor, a pump driven bysaid motor for maintaining a supply of fuel to Vsaid valve, a brake forretarding the operation of said pump, and means responsive to pumpdischarge pressure above a given value for actuating the brake. Y

4. In a device for controlling liquid fuel flow to a burner, thecombination with a casing having an inlet and an outlet, a valve in saidinlet, a float operatively connected to said valve to openrand close thevalve to maintain a prede-jY termined fuel level in the casing, of apump connected to a source of fuel and to said inlet for delivering fuelunder pressure to said inlet, a continuously energized motor, andraflexible coupling connecting said motor and said pump for storing energyupon relative rotation therebetween, the pressure rise incident toclosure` of said valve and continued operation of said motor beingoperable to stall said motor, said coupling being operable to storeenergy and maintainV the pressure when said motor stalls. Y

5. In a Vdevice for controlling liquid fuel ow tc a burner, thecombination with a casing having an inlet and an outlet, a valve insaidinlet, a iloat operatively connected to said valve to open and' closethe valve to maintain a predetermined fuel level in the casing, of aconstant volume REFERENCES CITED The following references are of recordin the le of this patent:

UNITED STATES PATENTS Number 10 Number Name Date Fritz Nov. 27, 1917Wilson June 9, 1931 Teesdale June 20, 1935 Harrington May 1.8, 1943Johnson July 13, 1948 FOREIGN PATENTS Country Date Germany 1932

